It took Ford another two years to downsize; the 1978 LTD had a wheelbase of 121 inches, but for the 1979 model, they chopped 7" off to give 114", while overall length went from 224" to 209" and width 79.5" to 77.5". Apparently they didn't lose any interior room according to these figures from their 1979 literature. I would imagine it would have been the same story with GM when they downsized for 1977. Both companies must have done some really insightful thinking.